Metal spray coating mechanism



Aprifi 25, 1950 J. H. DAVIS 2,505,530

METAL SPRAY COATING MECHANISM Filed April 16, 1948 v 2 Sheets-Sheet l mvsmon 12mm; ii flaws HTTORNEY April 25, 1950 J. H. DAVIS 2,505,530

METAL SPRAY COATING MECHANISM Filed April 16, 1948 2 Sheets-Sheet 2 INVENTOR Jam 17. Jami;

ATTORNEY atentecl Apr. 25,, 1950 WTAL SPRAY CQd'EGi MEG James W. Davis, Verona, Pa", asslgnor to Alandhum llompany oi America, Pittsburgh, ha, a corporation oi Pennsylvania Application April ill, l94t,'$erlal No. 21.3%

Wt. Eli-J22) ii mainline This invention relates in general to new and improved mechanism or apparatus for applying spray coatings to workpieces, such as extruded shapes, rolled sections, sheet, plate, bar and rod, ingots, castings. tubing and the like, by means of spray nozzles which direct a coating material against the surface or surfaces of a workpiece to be coated.

The apparatus or mechanism of the invention has found commercial success in its application to aluminum and its alloys wherein it is required to coat previously shaped or formed structural aluminum alloy members with a corrosion resistant aluminum or aluminum alloy coating. It is not, however, intended that the apparatus or the invention be limited in its use to any particular metal or alloy since the material to he coated and the coating metal are not controlling factors.

It is an object of the present invention to provide integrated mechanism or plant for spray coating practice, which is flexible in its design and operation to accommodate a variety of shapes and sizes of workpieces.

It is another object of the invention to provide a mechanism or apparatus for spray coating operations, which incorporates means for indexing a workpiece fed through the apparatus in a manner to imure complete coverage of its surface.

A further object of the invention is to provide a metallic spray coating mechanism which adapts itself to th application of metallic coatings of uniform thickness and width along the length of a workpiece fed thereto in continuous fashion.

Other objects will present themselves on consideration of the following specification, when read in conjunction with the drawings, in which:

Fig. 1 represents a top plan view, in partial section, of a spray coating apparatus incorporating features or the invention;

Fig. 2 represents a front elevational view of the apparatus taken in the direction of the arrows 11-11 of Fig. 1;

Fig. 3 represents an end elevational view taken in the direction of arrows IIIIII of Fig. 2;

Fig. 4 represents a sectional elevation taken along the line IVIV of Fig. 1;

Fig. 5 represents a View similar to Fig. i following an indexing operation;

Fig. 6 represents a fragmentary view, in partial section, to an enlarged scale, taken along the line Vii-VI of Fig. 2;

Fig. 7 represents a top plan view of a. spray nozzle to an enlarged scale; and

Fig. 8 represents a sectional elevation taken along the line VIIIVIII of Fig. 7.

In general, the apparatus of the invention comprises a reservoir or furnace for maintaining and containing a supply of molten coating 1L having one or more spray nozzles. preferably asill til

till

pirating or atomizing nozzles, in communication with the molten metal supply. A source of compressed air or gas, preferably heated, is connected to each spray nozsle, and indexing and feeding equipment or devices are located on either side of a single or bank of spray nozzles for translating a workpiece through an atomized spray zone of coating metal.

In more specific terms, a holding and/or melting furnace it, provided with a projecting baywindow it, is employed to serve as a reservoir for a supply of molten coating metal. The baywindow section of the furnace is provided with a cover plate it upon which one or more atomizing nozzles iii are suitably supported to extend downwardly into the molten coating metal in the furnace. Compressed air, or other gas, delivered to a temperature raising furnace it is conducted to each of the atomizing nozzles it as by means of suitable conduits or pipes it. A valve is may be installed in the compressor line to insure a constant adjustable pressure.

Indexing and feeding devices, represented in their entirety by the reference numeral 20, are located on either side of the bay-window it. These devicesare identical in their construction and like reference numerals identify similar parts in each unit.

Each indexing and feed mechanism includes a pair of arcuately curved channel sections it and it secured in aligned and spaced relation ship through the medium of a base plate it and a top plate ill. The plates it and El may be attached to the channel members 2d and ill as by welding or riveting to produce a rigid structure.

A feed roller {it is axially journaled within plate members it and ii and is directly con nected through a suitable coupling to a variable speed synchronous motor it rigidly secured to the underside of bottom plate 2t. Idle guide rolls it are also journaled in the plates 26 and ii on either side of the feed roll 30.

A suitable crosshead i4 is slidably mounted upon the top surface of bottom plate it, a fluid operated cylinder and piston arrangement 35, rigidly afilxed on the bottom plate 26, serving to translate crosshead 34 upon the upper surface of bottom plate 26. The crosshead 3t rigidly supports a frame structure 36 within which is mounted idle guide rolls ll and 38.

Work clamping or hold down rolls MI and 42 are provided in cooperation with the aforedescribed guide and feed rolls in each of the indexing and feeding devices 20. The rolls to and it are supported in suitable stanchions 4! secured to the upper surface of bottom plate member 26. In the preferred construction the lower roll 4|] is journaled in fixed bearings M whereas the upper roll '52 is journaled in quick release bearing blocks 55, which construction permits ready adjustment of the pass between the clamping rolls 40 and 42 for varying depths of workieces. p Each indexing and feeding mechanism 20 is supported upon four flanged rollers 48 that are journaled in bearings preferably formed integral with standards 50 located on either side of baywindow l2. One of the rollers 48 of each of the feeding and indexing devices 20 is provided with a pinion in mesh with a gear segment secured to the web of arcuate channel member 25. Additional driving pinions 52 are secured to the ends of a through shaft 54 journaled in bearings formed integral with the standards 50. The pinions 52 are mounted for meshing engagement with the pinions 5| and a variable speed electric motor and gear reducer drive 55 serves to impart simultaneous oscillatory drive for the indexing and feeding mechanisms over the arcuate periphery of channel members 24 and 25. The motor gear reducer unit 55 may be supported upon an outboard platform 56 forming an integral portion of the standard 50 as viewed in the right hand indexing and feeding mechanism in Figs. 1 and 2. Otherwise the standards 50 are identical in their construction and may be all-cast units.

In any metal spraying operation, and in particular any practice of projecting metal in a spraying operation in accordance with the volumetric capacity and particle size range contemplated, described and claimed in copending application Serial No. 21 324, filed April 16, 1948, an industrial explosive hazard presents itself. In view of this condition, it has been found essential in the practice of the present invention to provide sufiicient exhaust fan and dust collecting capacity to insure elimination of excess dust or metal spray that is not employed in an actual coating operation.

Any dust collecting system employed with the present apparatus must of necessity have suflicient-capacity to remove that portion of the atomized spray which is not applied to a. workpiece during a coating operation. In the preferred form of the invention it has been found desirable to incorporate a central exhaust stack 58 which is disposed directly above the effective area of the atomizing nozzle or nozzles mounted in the bay-window 12 of furnace III. This stack is of sufficient area to completely encompass the area of the spray or sprays produced by the atomizing nozzle or nozzles l5 and is located immediately above the path of travel of a workpiece 60. Additional exhaust stacks or conduits 59, preferably two or more, are also em ployed, their location being below the path of travel of the workpiece 60. As illustrated in Fig. 2 the auxiliary exhaust stacks 59, in response to their location, insure removal of atomized metallic particles which are turned back toward the nozzle or nozzles as a result of a rebounding action off the surface of the workpiece 60. Exhause stacks 58 and 59 are incorporated in a suitable dust collecting system that includes a single or separate exhaust fan of such capacity that all unused atomized metallic powder or metal particles is withdrawn from the immediate vicinity of a spray nozzle l5. As a direct result of this dust collecting exhaust system the explosive hazard is eliminated and the auxiliary stacks 59 further insure against clogging of a nozzle l5 by build-up of metallic particles rebounding from the underside of a workpiece 60 during a coating operation.

A workpiece pre-heating device or furnace 62 may be incoporated in the present apparatus.

This pre-heating mechanism may take the form of an electrical induction coil, an oil or gas fired furnace, or any other form of industrial heater. It is preferably located between the indexing and feeding mechanism and bay-window I2 on the feed or charging side of the apparatus, as indicated by the directional arrow of feed in Fig. 1.

The nozzle [5 that has been found satisfactory for use in cooperative association with the mechanism thus far described is preferably of the aspirating or atomizing type and is illustrated in more detail in Figs. 7 and 8. The preferred form of nozzle comprises a head or body member having a dependent, preferably vertical, tubular passage 66 extending below the level of molten coating metal in the furnace l0 and bay-window I2. A discharge orifice or nozzle tip 68, preferably constructed from suitable ceramic material, is centrally located in the upper portion of body member and is surrounded by a jet forming plate 10 which cooperates with an air or gas chamber 12 formed in the nozzle body immediately below the plate 10.

The chamber 12 is connected to the compressed air or gas supply, preferably in a heated condition, by means of the conduit l8, and a whirl ring or spirally vaned annulus 14 may be provided in the chamber 12 to impart a, whirling movement to the gas or air discharged through the annular orifice formed between plate 70 and nozzle tip 68. This whirling action aids in effecting a more thorough disintegration of the molten metal through convering the air or gas blast around the periphery of the stream of molten metal discharged through the nozzle tip 68.

If desired, auxiliary ports 16, disposed on diametrically opposite sides of the discharge nozzle 68, may be employed to flatten out what would otherwise be a conical spray of circular target area emanating from the nozzle tip 58.

In the operation of the apparatus or mechanism of this invention, sections of workpieces 60 to be coated, with or without a preparatory surface treatment, such as mechanical roughening or chemical etching of the same, have their leading ends introduced between hold-down or clamping rollers 40 and 42, as viewed from the right of Figs. 1 and 2. A workpiece 60 must be advanced a sufficient distance through the indexing and feeding mechanism to permit lateral engagement between idle guide rollers 32 and feed roller 30 on one side of the section of the workpiece 60 and idle guide rollers 31 and 38 on the opposite side of the workpiece 60. Engagement of the workpiece as thus described is accomplished through manipulation of the fluid operated piston and cylinder mechanism 35. The upper clamping roll 42 may now be brought into clamping relationship with the uppermost surface of the workpiece 60.

The workpiece 60 may now be advanced across the bay-window l2 and through the atomized spray emanating from one or more of the nozzles l5. This advancing movement or translation of a, workpiece is accomplished through manipulation of synchronous motors 3|. It will be appreciated that the left hand indexing and feeding mechanism, as viewed in Figs. 1 and 2, will perform in the same manner as described for the right hand indexing and feeding mechanism.

By manipulation of motor reducer unit 55 both indexing and feeding devices 20 may be simultaneously moved to permit angular disposition of a workpiece 60 in respect to the relatively fixed target area of the coating spray emanating from a nozzle l5. This is illustrated to best advantage in Figs. 4. and 5 wherein it will be seen that an uncoated surface may be presented to the nozzle spray as desired or required. This is of particular significance when it is considered that workpieces of a width greater than the effective Width of a spray must be translated through the spray two or more times to obtain full width spray coverage. Adjustment of the indexing and feeding mechanisms also provides means for directing an otherwise fixed spray to internal portions of workpiece being coated, such for example as the inner flanges of an I-beam or the like.

The various adjustable features of the mechanism, including synchronous motors 3| controllable through a variable speed range, adjustable gas or air pressure controllable through valve l9, and adjustable indexing of a section relative to spray nozzles l5, result in a wide degree of flexibility for the apparatus of the invention.

Although the apparatus of the invention has been defined in terms of a single installation and arrangement of mechanical elements, it should be understood that the invention is not to be limited thereto except as defined in the appended claims.

What is claimed is:

1. A spray coating mechanism comprising an atomizing nozzle directing a spray of coating material in a fixed target area, a feeding device for advancing a workpiece through said target area, and an exhaust system for removing and collecting excess coating material, said exhaust system having spray collecting inlets disposed laterally with respect to the atomizing nozzle and betweer. the workpiece and the atomizing nozzle.

2. A spray coating mechanism comprising a spray nozzle directing a spray of coating material in a fixed target area, a feeding device for advancing a workpiece through said target area, and an exhaust system for removing and collecting excess coating material, said exhaust system having excess spray collecting inlets adjacent and laterally beyond the surface of the workpiece being coated.

3. In a metallic spray coating apparatus, a spray producing zone comprising at least one atomizing nozzle providing metal spray, an indexing and feeding device located on either side of the spray producing zone, synchronously driven workpiece feed rollers in each indexing and feeding device, workpiece guide rollers and clamping rolls in each indexing and feeding device, and an exhaust system in communication with said spray producing zone, said exhaust system having spray collecting inlets laterally disposed with respect to said spray producing zone and between a spray producing nozzle and a surface being sprayed.

4. In a metallic spray coating apparatus, a source of molten coating metal, an atomizlng nozzle depending into said coating metal, a source of compressed gas connected to said atomizlng nozzle, feeding mechanism for advancing a workpiece over said atomizing nozzle, and a dust collecting system having an inlet laterally disposed adjacent the surface of a workpiece being coated and between the nozzle and said surface.

5. In a metallic spray coating mechanism, a furnace for maintaining and containing a supply of molten coating metal, an aspirating nozzle associated with the molten metal supply, a source of compressed gas connected with the nozzle and ing and feeding mechanism for adjustably positioning and advancing a workpiece over the nozzle and through the spray discharged therefrom, and a dust collecting system of such capacity and arrangement of dust collecting inlet: to insure elemination of metallic spray in excess to that applied as a coating, said dust collecting inlets being located laterally with respect to th metallic spray and between the workpiece an the aspirating nozzle. i

6. In a metallic spray coating apparatus hav ing a volumetric capacity in excess of the coatin; metal applied during a spray coating operation a nozzle for directing the spray coating agains a surface to be coated, feeding means for con tinuously presenting an uncoated surface int spray coating position, and an exhaust system having an inlet disposed adjacent and lateral t the surface being coated and the nozzle produc ing the spray coating, whereby excess coatin: spray is removed from the vicinity of the nozzle '7. In a metallic spray coating mechanism hav ing a volumetric capacity in excess of the coatin; metal applied during a spray coating operation, l nozzle delivering a spray of definite and relative]; fixed target area, feeding means for presentin: an uncoated surface through said target area ii a lineal direction, means for indexing said feed ing means laterally in respect to said lineal di rection of feed, and an exhaust system havin; an inlet disposed between and laterally to sail nozzle and the surface being spray coated, where by excess coating metal is removed from th vicinty of the nozzle.

8. A spray coating mechanism comprisim means for delivering a spray of coating materia in a relatively fixed target pattern, feeding mech anism for advancing a surface into said targe pattern, indexing means mechanically connectei with said feeding mechanism for laterally p0 sitioning the surface relative to said target pat tern, and spray exhaust means having an inle disposed between and laterally to the spray de livering means and surface being coated.

9. In a metallic spray coating apparatus, spray producing zone including at least on atomizing nozzle providing a metal spray, an in dexing and feeding device located on either sid of the spray producing zone, workpiece feel rollers incorporated in each indexing and feed ing device, workpiece guide rollers and clampinl rolls in each indexing and feeding device, a syn chronous electric motor connected to each feel roller and supported by its complementary in dexing and feeding device, and an exhaust sys tem in communication with said spray producini zone, said exhaust system having spray collect ing inlets disposed between and laterally to a spray producing nozzle and a surface balm sprayed.

JAMES H. DAVIS.

REFERENCES CITED The following references are of record in th file of this patent:

UNITED STATES PATENTS Number Name Date 434,375 Bryant Aug. 12, 189 1,124,858 Caruso et al Jan. 12, 191! 1,264,358 Willwerscheid Apr. 30, 191: 1,266,669 Eberhart May 21, 1914 1,347,994 Day July 27, 192 1,643,330 Barord Sept. 27, 192' 

